The invention relates to a channel entering method for a wireless communication system, in particular an indoor network, comprising a plurality of subscriber stations, each of said subscriber stations having a transmitter and a receiver, whereby information can be independently exchanged between said subscriber stations using respective transmitters and receivers and a plurality of channels available for communication in said wireless communication system. The invention further relates to a subscriber station fore a wireless communication system.
For private homes and also local area networks (LAN) developments are going on to connect all kinds of devices together, as TV, personal computer, stereo systems, telephone etc. Several devices located in an area and belonging to a group of dedicated users, for example in the same apartment or in the same building, may be considered to be part of a so-called cluster. This may also include near-by-stations outside the respective building. Information exchange between the devices of the cluster and optionally between the cluster devices and stations of other near-by-clusters may be based on wireless RF communication. However, a combination of wireless and wireline RF communication may also be provided.
For the RF communication between the devices and/or the outside stations there will only be a limited number of RF channels available. Devices of a cluster, and/or optionally such of different clusters which communicate with each other, use one (or optionally more than one) channel by sharing a plurality of time and/or frequency slots. This normally causes no interference problems. The devices and the stations of the various clusters may use/reuse the RF channels available for communication under certain conditions (distance, interference level, etc.). Therefore, communication signals from devices in other clusters in most cases cause interference problems with respect to communication of the devices of the cluster considered. In situations of high communication traffic, interference may prevent a reuse of the same channel and, if no more channels are available, it blocks usage of a desired service.
In order to avoid conflicting situations, before entering and using a preferred channel for communication each device separately performs a channel testing procedure. In the channel testing procedure, on the basis of communication parameters the preferred channel is tested whether it enables wireless communication, preferably optimised communication over the preferred channel.
It is an object of the present invention to disclose a channel entering method for a wireless communication system for improving communication channel efficiency.
According to the invention a channel entering method for a wireless communication system, e.g. an indoor network, comprising a plurality of subscriber stations is provided, each of said subscriber stations having a transmitter and a receiver, whereby information can be independently exchanged between said subscriber stations using respective transmitters and receivers and a plurality of channels available for communication in said wireless communication system, said method comprising the steps of:
1. Method for channel entering in a wireless communication system, in particular an indoor network, comprising a plurality of subscriber stations (S1 to Sn, nxe2x89xa72), each of said subscriber stations (S1 to Sn) having a transmitter and a receiver, whereby information can be exchanged between said subscriber stations (S1 to Sn) using respective transmitters and receivers and a plurality of channels available for communication in said wireless communication system, said method comprising the steps of:
a) using a first set of communication reference parameters (I1, M1) to test a group of channels (C1 to Cm, mxe2x89xa72) of said plurality of channels available for communication between a first and a second subscriber station (Sx, Sy; 1xe2x89xa6xxe2x89xa6n, 1xe2x89xa6yxe2x89xa6n) of said plurality of subscriber stations (S1 to Sn);
b) selecting, if a channel (Cx, 1xe2x89xa6xxe2x89xa6m) of said group of channels (C1 to Cm) meets said first set of communication parameters (I1, M1), such channel for said wireless communication between said first and said second subscriber station (Sx, Sy);
c) testing said selected channel (Cx) by means of a directional antenna with a second set of communication parameters;
d) accepting said selected channel (Cx) for further wireless communication between said first and said second subscriber station (Sx, Sy) and possibly further stations, if said channel meets said second set of communication reference parameters (I2, M2).
The disclosed method improves the utilisation or channel efficiency and avoids negative consequences due to more frequent (re)use of the channels in wireless communication systems. On the basis of information derived from channel testing by means of a directional antenna second communication reference parameter are provided, which in turn are used to decide whether a selected channel may be used for further communication. Using the directional antenna for channel testing in the channel entering method allows distinguishing channels with a relatively high interference power in one direction different to the sought communication direction and channels with a relatively high interference power in all directions. At least for the connections to stations located in a direction opposite to the direction of the main interferer, some other communication reference parameters can be accepted which are less demanding. If results received from directional antenna detection are taken into consideration, likelihood will increase that a channel is entered which meets communication parameters necessary for correct communication between subscriber stations in the wireless communication system. Therefore, the method disclosed improves efficiency of wireless communication in the system and decreases the overall failure rate of the wireless communication system.
Further advantageous embodiments are apparent from the dependent claims.
The invention also relates to a subscriber station for a wireless communication system, which subscriber station utilizes the method specified above.